The influence of moisture content and storage temperature on the viability of Shoreaalmon, Shorearobusta, and Shorearoxburghii seed

Abstract

Seed of Shoreaalmon Foxw., Shorearobusta Gaertn. f., and Shorearoxburghii G. Don was subjected to desiccation treatments or retained at several different temperatures on 1% agar or in various containers; viability and moisture contents (wet-weight basis) were assessed periodically. Germination ability declined when moisture contents were reduced below approximately 35% for S. roxburghii, below a value exceeding 40% forS. almon, and below 40% for S. robusta; a straight-line relationship was observed between the probit of germination and moisture content percentage. When all three species were kept on agar at 2, 6, or 11 °C little or no germination resulted; on transfer to 26 °C after 153, 54, and 30 days for S. roxburghii, S. robusta, and S. almon, respectively, negligible further germination occurred. Similar chilling damage occurred in S. robusta and S. almon at 16 °C. Mean germination times were twice as long at all temperatures tested for S. roxburghii as they were for the other species. Storage at near 40% moisture content in ventilated containers at 16 °C enabled survival of S. roxburghii seed for 9 months with over 50% viability, whereas other species declined in viability to near 20% within 14 days. A sudden loss of viability within 24 h was observed for seed of S. robusta placed in 11 or 6 °C; in the subsequent few days, little further loss of viability occurred. With 40% moisture content, seeds of all species at 21 °C stored as well as or better than those at lower temperatures. Retention for short periods in closed containers quickly reduced germination for S. robusta and S. almon.